Technical advances in radical retropubic prostatectomy techniques for avoiding complications. Part I: apical dissection

Authors


R. Gillitzer, MD, Urologische Universitätsklinik Mainz, Langenbeckstrasse 1, 55131 Mainz, Germany.
e-mail: gillitze@mail.uni-mainz.de

SUMMARY

Radical retropubic prostatectomy is currently the most widely used surgical treatment for localized prostate cancer. This once cumbersome procedure has developed technically over the last 20 years, reducing dramatically the associated complications and morbidity, e.g. blood loss, incontinence and impotence. Currently the operation is safe and is the best choice for eradicating localized disease, with little loss in quality of life. However, differences in reported outcomes indicate that there is still a need for standardization and continued efforts for surgical excellence. This review focuses on the crucial steps of the procedure, in two parts: the first covers apical dissection and the second the steps related to vesico-urethral anastomosis and the nerve-sparing procedure. This evaluation of the technical modifications aims to offer a choice, to vary the procedure according to the individual situation and thus improve the results. Current trends in surgical technique are also presented.

INTRODUCTION

Currently radical prostatectomy (RP) is the method of choice for treating localized prostate cancer. The introduction of PSA assays in the early 1990s improved dramatically the diagnostic capability to detect prostate cancer at an early stage. The surgical technique of RP has been produced through a long phase of development and different approaches have been described. The definitive breakthrough in RP was made ≈ 20 years ago with the introduction of an anatomical approach to the gland. Since then, various modifications have been proposed in an attempt to refine the technique and improve the results. The prostate gland can basically be approached through a retropubic or a perineal incision. Recently, the laparoscopic retropubic technique has gained substantial interest, although its use is still confined to specialized centres.

Based on a thorough review of publications gathered from Medline and PubMed for the last two decades, and from our personal experience, this review provides a focus on specific innovative steps that have simplified the procedure and diminished the associated complications. We focus solely on the retropubic approach, as this is the most widely used surgical route to reach the gland.

RETROPUBIC RP

Retropubic RP (RRP) is derived from the procedure described by Millin for BPH in the 1940s, and later adopted for treating prostate cancer by Chute in the 1950s. In the earlier period, because there was little information on the anatomical details, RRP had a high morbidity of continence and potency. However, the anatomical studies of Reiner and Walsh [1] clarified the relationship of the prostate to Santorini's plexus and led to the introduction of an anatomical approach to the gland, to minimize blood loss and optimize exposure. The standardization of this technique set a milestone for further technical refinements over the last 20 years. Using cadaveric preparations (male stillbirths), Walsh and Donker [2] elucidated the exact course of the cavernosal nerves, providing fundamental topographical knowledge to develop the nerve-sparing procedure. The prostate can be removed in an antegrade (descending) or retrograde (ascending) manner. Technical improvements resulting in better visualization of the key structures have been critical in reducing intraoperative blood loss and increasing the rates of continence and potency, leading to a general acceptance of this procedure. Equally important, better surgical techniques with a precise dissection have helped to reduce the rates of iatrogenic positive margins.

Several key steps in RP deserve special attention, as the outcome of the procedure can be jeopardized if they are not performed precisely. However, if followed step-by-step, they will guarantee easy progress in the procedure.

INCISION AND OPERATIVE SITE EXPOSURE

The patient is placed supine with a partial table break at the level of the hips, which will open the operative site. This, combined with a slight Trendelenburg tilt of the table, will improve viewing. RRP is usually performed through a suprapubic midline incision up to the umbilicus. The linea alba of the anterior rectus sheath is incised and both rectus abdominis muscles separated. Identifying the pyramidalis muscle will aid in finding the midline. The posterior rectus sheath of the upper part of the incision and the transversalis fascia are incised and the space of Retzius developed by retracting both rectus muscles laterally. Caution is needed when placing the retractor blades, to avoid injuring the epigastric vessels; the vessels should be protected by leaving them covered with the transversalis fascia. Several types of ring retractors (Bookwalter, Siegel, Turner-Warwick) or a Balfour retractor can be used. The use of a table-fixed self-retaining retractor can obviate the need for a second surgical assistant [3,4], but frequent repositioning of the blades through specific steps of the procedure may be time-consuming.

Experienced surgeons perform the procedure through a very limited incision, of < 10 cm, with equivalent results and complication rates [3]. To reduce postoperative pain and improve the cosmetic results, a Pfannenstiel incision has also been proposed [5]. A comparative study with the classical approach showed a 44% reduction of requirements for analgesics in this group and no significant incision-related complications.

Wedge resection of the symphysis pubis has been suggested to improve apical exposure in difficult cases when the prostate is located deep in the pelvis [6]. However, this manoeuvre must not be used, because it may cause increased morbidity and incontinence [7], and the urethral stump can be readily accessed by other less traumatic means.

Rarely, a pronounced osteophyte will be encountered on the dorsal aspect of the pubic bone, hindering viewing and manipulation of the prostatic apex. It may be resected with an osteotome and rongeurs, as described [8].

MANAGING THE PUBOPROSTATIC LIGAMENTS

To expose the puboprostatic ligaments, the loose fibrofatty tissue overlying the endopelvic fascia must be removed; this is best done by using forceps with electrocautery or a Kittner dissector. By doing this carefully the superficial dorsal vein, which emerges between the puboprostatic ligaments, will become visible. This vein can be controlled with electrocautery if it is of small calibre, otherwise it should be ligated or clipped; a thin ligature should be used and tied gently, as the vein is fragile and can be avulsed easily.

The puboprostatic ligaments are an extension of the endopelvic fascia and a component of a urethral suspensory mechanism to the pubic symphysis [9]. They are paired, inverted V-shaped ligaments with one insertion at the symphysis and two at the anterior prostatic capsule. In RRP they must be transected to gain access to the dorsal vein complex and urethra. However, the dorsal veins are immediately underneath the puboprostatic ligaments and a transection close to the prostate may induce significant bleeding. Therefore, it is warranted to divide them close to the symphysis in small increments, exposing the veins of the dorsal complex that emerge between the legs of the inverted-V [6]. Avoiding excessive transection will not only prevent injury to these veins but may also preserve fixation of the urethra to the bone, and possibly be advantageous for continence [3].

PUBOPROSTATIC LIGAMENT-SPARING TECHNIQUE

In an attempt to improve continence some authors have modified the technique to leave this suspensory mechanism intact [10,11]. The puboprostatic ligament-sparing technique entails a wide incision of the endopelvic fascia just lateral to the puboprostatic ligaments from the pubic bone insertion up to the bladder neck, and then passing a suture ligature underneath the dorsal vein complex with no previous transecting of the puboprostatic ligaments. This necessitates dividing the puboprostatic ligaments/dorsal venous complex close to the prostate, instead of near their insertion to the pubic symphysis, and following a dissection plane between the dorsal vein complex and the anterior surface of the prostate, reflecting the pelvic fascia upwards as in perineal prostatectomy. The tissue containing the dorsal vein stump can be included in the anteriorly placed anastomotic sutures to re-establish the anterior support of the urethra. Care must be taken while dissecting the anterior prostate surface to prevent iatrogenic positive margins. However, continence results are somewhat contradictory [10,11] and further studies on larger patient cohorts must be awaited to draw any conclusions. Analysing a small cohort (25 patients with standard apical dissection vs 18 with puboprostatic ligament-sparing technique), Poore et al.[11] found no difference in continence rates in the two groups. Only the time to return of continence was improved in the ligament-sparing group. Neither did they report a significant difference in the rate and location of positive margins. On the contrary, Lowe [10] found a statistically significant improvement in time to return of continence and total continence rates for this technique compared with the anatomical RRP with and without bladder neck preservation, and to RRP with bunching of the dorsal vein plexus. Of 51 evaluable patients with ligament preservation, 26% and 96% regained continence immediately after catheter removal and at 6 months, respectively. Of the 35 patients followed for> 1 year, only one reported using any protection (i.e. 1–2 pads a week), i.e. all required fewer than one pad/day. Furthermore, blood loss was considerably less while the margin positivity of the specimen was not adversely affected.

Lynn Avant et al.[12] used a specially designed sound that, after being introduced transurethrally, allows a suture to be placed that embraces the dorsal vein complex. To keep the urethral suspensory mechanism untouched, they did not incise the puboprostatic ligaments, and fixed the dorsal vein complex suture to the pubic bone. For the initial 35 patients so treated, the time to regain continence was only 4.2 weeks. On postoperative urodynamic evaluation the authors also reported a gain in functional urethral length, in contrast to the standard prostatectomy technique, which they accounted for by anchoring the urethra to the bone, as it cannot retract into the genitourinary diaphragm.

CONTROL OF THE DORSAL VEIN PLEXUS (SANTORINI) AND APICAL DISSECTION

Understanding the anatomy of the dorsal vein plexus is essential for RRP, as this is the main source of bleeding. The vein plexus emanates from underneath the pubic symphysis, draining blood from the penile dorsal vein. It is encased beneath the puboprostatic ligaments and travels on the ventral and lateral surfaces of the prostate, forming an intricate net of delicate and dilated veins with many anastomoses. It gives off a superficial branch which emerges between the puboprostatic ligaments and runs anterior to the pelvic fascia in the preprostatic fat. However, the main trunk of the vein plexus and lateral tributaries are concealed underneath the pelvic fascia, surrounded by a thin layer of tough connective tissue [9]. Control of this complex has always posed a challenge to the surgeon, as bleeding can be caused with minimal manipulation and repair is difficult because of the many sinus-like connections between the veins, the fragility of the vein walls, and because there is little connective tissue to support a suture. Furthermore, the external striated sphincter which surrounds the membranous urethra is in intimate contact with the overlying vein plexus and may be injured while trying to attain haemostasis [13].

Walsh emphasized the importance in assuming early control of Santorini's plexus. This manoeuvre provides a relatively bloodless operative field with excellent exposure, which is the basis for ensuring a precise dissection of the prostatic apex.

The apex is the most common site of positive margins in RRP [14–16], especially by inadvertent incision of the prostate capsule. This is partly explained because the fibrous capsule of the gland is not well defined at the apex. However, the topographical location of the prostate, with the apex being localized underneath the pubic symphysis, surgical dissection close to the prostate to avoid injury to the dorsal vein plexus, and preserving as much urethral length as possible, are also contributing factors. Myers et al.[17] showed that differences in prostatic apical shape must be expected during dissection. Furthermore, the quality of apical dissection will influence postoperative continence, and potency in nerve-sparing procedures.

The anatomical studies by Walsh in the early 1980s provided the necessary insight to make several modifications to the surgical technique that led to a significant reduction in haemorrhage from this site [13]. These alterations included:

  • • Opening the endopelvic fascia adjacent to the pelvic sidewall at a sufficient distance from the prostate to prevent injury to the lateral venous plexus.
  • • Careful division of the puboprostatic ligaments because the main tributaries of the dorsal vein plexus are encased underneath them.
  • • Selective ligation of the common trunk of the dorsal vein over the urethra.

THE ‘BUNCHING TECHNIQUE’ OF THE DORSAL VEIN COMPLEX

Several technical steps have been proposed to manage the dorsal vein complex. Once the endopelvic fascia has been opened bilaterally and the puboprostatic ligaments divided (or not), most surgeons attempt to find the cleavage plane in the avascular layer between the dorsal vein plexus and the urethra. To facilitate exposure of the prostatic apex, the surgeon may place ‘longitudinal bunching sutures’ that grasp both the medial (prostatic) edges of the incised endopelvic fascia and compress the dorsal vein plexus by suturing them to each other in the midline from the prostatovesical junction to the apex [18]. The purpose of these sutures is to improve visualization of the anterolateral surface of the prostate and to evaluate apical shape, which may be of substantial help in dissecting the neurovascular bundles. According to Myers et al.[18], proper haemostasis is not achieved by this bunching technique, but with a correctly placed distal suture of the dorsal vein complex. We used this technique but noticed that apical dissection was significantly more difficult if the puboprostatic ligaments were not previously completely transected. However, bunching sutures on the ventral surface of the prostate will prevent back-bleeding from the vesical veins [3,19].

SELECTIVE CONTROL OF THE DORSAL VEIN COMPLEX

In the past, the main trunk of the dorsal vein complex was ligated with the help of a right-angle clamp, as described by Reiner and Walsh [1]. The clamp was passed underneath the vein plexus and a free ligature grasped at the other side. However, sometimes the plane between the urethra and the dorsal vein plexus was difficult to develop, and the right-angle clamp would injure these delicate veins, causing profuse bleeding that was not easily stopped; this made further dissection more difficult. Initiating a chain of adverse events, in a vigorous attempt to stop the bleeding, the surgeon would be tempted to place several haemostatic sutures, taking ‘big bites’. In doing so, the striated external urethral sphincter, which is better developed anteriorly, could be injured, risking postoperative continence [20]. Another disadvantage of passing a ligature on a right-angle clamp to control the vein plexus is that it may slip while transecting the plexus, inducing some haemorrhage. Lange and Reddy [6] avoided this by securing this ligature with a suture that is passed through the distal dorsal vein complex with a needle, and then under the complex in the space developed by the right-angle clamp, to create a ‘ligature suture’ of the area. The ligature may also be placed too proximal and not distal to the true apex, and dissection of the prostatic apex may become difficult while trying to avoid injury to the venous plexus or inadvertently dividing the ligature while transecting the plexus. Dissecting the ventral prostatic surface can be impossible, increasing the risk of inadvertently producing a positive margin at the apex.

Some authors prefer to develop the cleavage plane at the apex between urethra and the dorsal vein plexus with careful blunt dissection using the index finger, and then passing a steel wire that (under tension) acted as a template to permit selective division of the dorsal venous plexus [19].

Evidently, the refinement of technique introduced in the 1990s for managing the dorsal vein complex has been one of the most important contributions to RRP. Walsh and others [21] have abandoned using the right-angle clamp. The former now favours placing a 3/0 poliglecaprone suture in the dorsal vein complex and then, after turning the needle around in the needle holder, passing it through the perichondrium of the pubic symphysis [9,13]. If the dorsal vein complex is large, Walsh prefers to place two separate sutures to encompass the whole complex separately. By doing so he attempts to avoid bunching sutures, as they can result in inadvertent damage of sphincter substance and thus affect function of the sphincter mechanism. The suture through the perichondrium also provides anterior stability of the external sphincter, resembling the effect originally exerted by the puboprostatic ligaments. Indeed it also fixes the dorsal vein complex against the bone to obtain a better cleavage plane for the later apical dissection. After having secured the dorsal vein plexus and exerting downward pressure on the anterior surface of the prostate, the plexus can be sharply transected with a scalpel. Final venous control is achieved by selectively oversuturing the distal stump of the vein plexus. The plane of apical dissection towards the membranous urethra will then be clearly defined and an accidental incision into the anterior prostate surface will be unlikely.

Scardino et al.[22] use a similar technique for stabilizing the dorsal vein complex and for achieving perfect haemostasis. After sharply transecting the dorsal vein complex, they modified the technique in 1990 by vertically suturing together the edges of the endopelvic fascia over the distal stump of the dorsal vein complex, beginning at the symphysis towards the urethra and then back. The final stitch of this continuous suture is placed through the periosteum of the symphysis to fix it to the bone. Similarly, to prevent back bleeding, they use a running suture to adapt the cut edges of the endopelvic fascia over the prostate and the dorsal veins, beginning at the prostatovesical junction until the urethra is reached (Fig. 1). Furthermore, they emphasized leaving all periurethral tissue distal to the apex intact. In a multivariate analysis including 390 patients operated with this new technique, this change helped to increase considerably not only continence recovery rates, from 82% to 95%, but also reduced the median time to regain continence [22].

Figure 1.

The technique to control bleeding after dividing the dorsal vein complex. From [22] with permission. In nerve-sparing prostatectomy, some authors [32] do not recommend suturing together the proximal edges of the pelvic fascia over the prostate.

Renda and Marievoet [21] control the dorsal vein complex with a suture that protrudes from a transurethral sound. Another viable alternative is to engulf the dorsal vein plexus with a Babcock clamp once the puboprostatic ligaments have been transected, and to place a single or figure-of-eight transfixion ligature distal to it [20,23,24]. Digital sensation of the transurethral catheter will help to identify the correct plane for placing the clamp. An advantage of this manoeuvre is that the Babcock clamp will aid perfectly to bunch the dorsal vein plexus in the midline. This, and the possibility to feel the distal edge of the forceps with the needle, which should be located distal to the apex at the prostatomembranous junction, serves as a guide and facilitates placing the sutures.

TECHNICAL NUANCES IN APICAL DISSECTION

Recently, in an effort to minimize the incidence of positive surgical margins, a variation of surgical technique has been proposed that, respecting the above mentioned concepts, consists mainly of dividing the dorsal vein complex up to 15 mm and the urethra 3 mm distal to the apex, and by resecting a bladder neck cuff with the specimen [25]. For the 144 patients included the total positive margin rate of 11% was better than the 16–46% reported previously, and the rate of apical positive margins was second after posterolateral margins. However, the report did not evaluate continence, which may have been jeopardized by the extended apical dissection. In the last 3 years, the authors further refined the technique of apical dissection and reported a total positive margin rate of 4.9% (including 1.5% isolated positive apical margins) in 263 men [26]. The technique includes sharp dissection of the levator ani muscle at the border to the prostate, and sharp division of tissue lateral to the apex and membranous urethra before dividing the urethral catheter. Similarly, for clinical T2 tumours of < 2 mL, Villers et al.[16] reported a significant reduction in positive surgical margins, from 21% to 6%, after modifying the surgical technique. Adapting for tumour-spreading routes on histological findings, and based on a detailed anatomical knowledge, the apical dissection is meticulous, using the bunching technique of Myers. The authors emphasize some minor but important technical peculiarities. Cephalad traction on the prostate should be exerted at all times during apical dissection to improve visibility of the prostato-urethral junction. The division of the dorsal vein complex should not be perpendicular, and moreover it must adapt to the contour of the anterior fibromuscular stroma of the prostate. To avoid positive surgical margins at this level in transition zone cancers, some ligated dorsal vein complex tissue should be left on the apical prostate. Upward ventral traction of the prostate on a bladder catheter should be avoided while transecting Denonvillier's fascia in the midline, as this traction may cause this fascial layer to be avulsed off the prostate. Denonvillier's fascia is incised under vision, while the recto-urethralis muscle does not need to be transected to find the pre-rectal space anterior to the rectal wall. Wide excision of Denonvillier's fascia is continued up to the seminal vesicles.

CONTINENCE NERVE-PRESERVING TECHNIQUE

Both direct myogenic damage and sphincteric denervation injury may be responsible for stress urinary incontinence. The so-called ‘continence nerves’ have been isolated in cadaveric studies and further clinical analysis to detect possible mechanisms of damage during RP have been undertaken [27]. At the level of the prostatic apex, somatic and autonomic branches of the pudendal and pelvic nerves, respectively, enter bilaterally the external urinary sphincter at the 5 and 7 o’clock positions. Damage to these fine structures by tear or stretch is more likely while passing a right-angle clamp behind the urethra to develop a plane between the posterior rhabdosphincter and rectum, and if the urethral anastomotic sutures are placed at the 5 and 7 o’clock positions. Instead, the authors advocate placing sutures at the 8, 10, 2, 4 and a final suture at the 6 o’clock positions. The right-angle clamp may also damage the posterior fascial attachment of the urethral sphincter complex to the central tendon of the perineal body. Furthermore, injury to the autonomic pelvic plexus can be caused by excessive dissection of the tips of the seminal vesicles, which are located in its immediate vicinity. Denonvilliers’ fascia over the seminal vesicles should be sharply incised, to be left in situ as a protective covering of the nerve plexus, and the seminal vesicle artery should be controlled under direct vision. Direct comparison of a ‘continence nerve’-preserving operation and standard RP showed a significantly faster return to continence in the nerve-preserving group (65% vs 13.2%, respectively, by 1 week, and 93.3% vs 44.7%, respectively, by 9–12 weeks), but similar overall continence rates, indicating possible nerve regeneration or resolving neurapraxia [24,27].

SEMINAL VESICLE-SPARING RP

Besides the distal sphincteric mechanism, the integrity of the trigonal innervation and an intact pelvic-to-pudendal urethrosphincteric reflex may influence the recovery of continence after RP. Urinary continence in seminal vesicle tip-preserving RP was prospectively studied by John and Hauri [28], and compared with the standard procedure. The seminal vesicle tips were left in situ and excessive intraoperative manipulation of the surrounding tissues avoided to protect the autonomic nerve branches emanating from the pelvic plexus. There was a statistically significant difference, with a greater return to continence at 6 weeks and 6 months in the seminal vesicle group of 20 patients (60% and 95%, respectively), than after complete resection (18% and 82%, respectively). Furthermore, posterior urethral sensory threshold tests correlated with urinary continence. As shown by Korman et al.[29], failure to excise the tips of the seminal vesicles is unlikely to alter the prognosis.

INITIAL PERIRECTAL DISSECTION

If nerve-sparing is not attempted, Stephenson et al.[30] proposed an initial bilateral perirectal dissection plane directly on the posterolateral aspect of the prostate from base to apex that will ensure posterior and posterolateral wide excision. Capsular penetration is common at the posterolateral aspect of the prostate and using this plane of dissection has significantly reduced positive margins. At the end the longitudinal muscle fibres of the rectum will be visualized. This perirectal dissection is not associated with an increased rectal lesion risk [31].

CONCLUSION

The current trend in dissecting the dorsal vein complex is towards limiting excessive manipulation of the area of the external sphincter complex by selectively dividing superficially the puboprostatic ligaments, controlling the dorsal vein plexus with a needle suture, by not passing a right-angle clamp underneath, and not going further with dissection in the region of the external sphincter complex or dissecting the urethra extensively [3,13,16,20,24]. The implementation of these concepts has helped to significantly improve continence rates and the time to regain continence [3,20].

TAKE-HOME MESSAGE – SURGICAL TRICKS

  • • Do not use a right-angle clamp to develop the cleavage plane between the dorsal venous complex and the prostato-urethral junction; if used, do not open the branches.
  • • After sharp division of the dorsal vein complex, oversuture it with a running suture, not including the anterolateral striated sphincter.
  • • Do not use a right-angle clamp to dissect the space between the posterior rhabdosphincter and anterior rectum surface.
  • • Avoid placing urethral anastomotic sutures at the 5 and 7 o’clock positions.
  • • Avoid excessive dissection around the seminal vesicle tips (leave Denonvilliers’ fascia laterally intact).
  • • Control the seminal vesicle artery under direct vision.
Abbreviations
RP

radical prostatectomy

RRP

retropubic RP.

Ancillary